Vacuum flask



Fig. 1.1 is a front perspective view of my new design;

Fig. 1.2 is a front view thereof;

Fig. 1.3 is a back view thereof;

Fig. 1.4 is a top plan view thereof;

Fig. 1.5 is a bottom plan view thereof; and

Fig. 1.6 is a right side view thereof, the left side view being a mirrorimage thereof.

The broken lines and areas within them depict portions of the vacuumflask that form no part of the claimed design.

CLAIM The ornamental design for a vacuum flask, as shown and described.